It has been well established in the patent art and through technical literature that the heating of water has taken two principal system and equipment forms, i.e., continuous flow water heating and reservoir water heating. One classic form of known continuous flow water heating apparatus utilizes an electric resistance coil arranged in an "in line" housing through which cool or normal temperature water is directed on demand to obtain heated water. Known apparatus of this type includes a controller, responsive to a water temperature sensor, whereby alternating current power is switched "on" and "off" to the electrical heating coil of the apparatus based upon demand for heating the water flowing through the apparatus. Reservoir water heating, on the other hand, normally involves the use of one or more heat insulated water storage tanks wherein heated water is withdrawn on demand with heat applied by gas or electric energy to maintain a desired hot water issuance temperature throughout extended non-demand times.
Known electrical resistance "in line" water heating apparatus and systems have deficiencies in several important respects. Thus, such apparatus and systems have frequently employed an electrical resistance heating coil of U-shaped configuration which have commonly required frequent replacement due to burnout of the coil at the U-bend where heat is concentrated during heater operation. Further, such apparatus and systems tend to confuse accurate temperature sensing of the exit temperature of the flowing water. In U.S. Pat. No. 4,762,980, granted to H. Insley, excessive heating of the U-shaped coil at the U-bend area is allegedly avoided by shunting of the coil current in that area. In such patent an encased, thermistor-type temperature sensor (located proximate the U-bend of the heating coil) is connected to an external temperature controller which interconnects with an external switching unit for controlled intermittent energization of the coil.
It is a primary object of the present invention to provide an improved "in line" tankless electric water heater of compact size and ease of installation.
It is a further object of the invention to provide an improved continuous flow electrical resistance water heater which can be easily installed and serviced.
It is a still further object of the invention to provide an improved "in line" tankless electrical resistance water heater wherein the heating coil is of circular configuration and without a U-bend requiring shunting of the coil to avoid excessive heating of the coil in the bend area.
It is yet another object of the invention to provide an improved "in line" tankless electric water heater which is instantaneously responsive to the demand for hot water.
These and other objects and advantages of the present invention will become apparent from the following summary of the invention and detailed description thereof taken in conjunction with the accompanying drawing figures.